The objective of this program project application is to develop novel therapeutics that target CNS and peripheral reservoirs of HIV-1 replication. Under the auspices of a U19, we have identified novel small molecules that target the vif-apobec axis and that specifically inhibit vif-dependent viral replication. Structure Activity Relationship (SAR studies have identified potent analogs (IC50 <100nm) that are active in primary' macrophage, show CNS bioavailability and exhibit unique resistance profiles. We propose to build on these discoveries to optimize the activity and specificity of these small molecule vif antagonists and, on the basis of antiviral potency/specificity, Pk/Tox and resistance profiles, prioritize the most promising analogs for analysis efficacy in a SlV/macaque model of encephalitis. The individual projects and cores that constitute this program project application and their roles are as follows: Project 1. Tariq Rana, Ph.D., Sanford-Burnham Institute, Vif antagonism: lead discovery and SAR. Project 2. Mario Stevenson, Ph.D., University of Miami Medical School. Vif antagonism: Virologic support for SAR and molecular mechanisms of inhibitor resistance. Project 3. Susan Westmoreland, VMD, New England Primate Research Center. Vif antagonism: evaluation of efficacy in a macaque model of SIV-induced encephalitis. Core A, Administration. Mario Stevenson, University of Miami Medical School. Coordination of the activities of the individual components and interaction with the external Scientific Advisory Board. Core B. Agneta von Gegerfelt' Ph.D., Bioqual Inc. SIV viral load assays and small animal Pk/Tox studies. Bioqual, Inc. will serve as a non-academic core on this program project application. Studies undertaken in this program project will advance the development of a clinical candidate and set the stage for the clinical evaluation of vif antagonists as new agents for the treatment of HIV-1 infection.